TP 2: Android module
====================

Instructions
------------

* Subject tag: ``TP2``
* **Deadline: 08/07/2018 23h42**

Subject objectives
------------------

* Be able to use Android build system.
* Be able to write an Android makefile for a given project.

Subject
-------

Add `abootimg`_ tool to AOSP source tree.

.. note::
   For parts 1. to 3., you are allowed to bypass the review system.


Documentation:

* `Lecture slides <_static/sand-lectures2.pdf>`_
* Google documentation:

  * `Understanding 64-bit Builds`_
  * `Android.mk`_


1. Android sources setup
^^^^^^^^^^^^^^^^^^^^^^^^

CRI Android mirror:
   ``git@git.cri.epita.net:sand/aosp/``

Git repository name:
   module-manifest-<login>

Normally, you should have synced Android sources from CRI mirror, pointing to
``android-8.1.0_r33``.
However, on `gerrit`_, you have your own manifest repository ``module-manifest``.

On the side:

#. Clone your Gerrit manifest repository.

#. Fix your manifest so that:
   
  * Your work must be based on ``android-8.1.0_r33`` revision in a dedicated
    branch ``abootimg``.

  * ``aosp`` remote must be set to CRI mirror. Do not forget the review URL.

In your sync directory:

#. Reinitialize ``repo``.

#. Sync sources.


2. Add abootimg project in AOSP sources
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Git repository name:
   abootimg-<login>

From now on, you can work locally in your sync directory. In your manifest:

#. Add a ``sand`` remote correctly pointing to `gerrit`_.

#. Add ``abootimg`` project.

.. hint::
   Be careful where you put ``abootimg`` project in the source tree ! It does matter
   (at least, for me) !

3. Write a dummy Android makefile
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The objective is to translate the local ``Makefile`` into a very simple Android
makefile.

Your work must be available in a branch called ``aosp``, bases on ``master``.

#. Create a ``version.h`` header file where the version must be ``aosp``.

#. Write the Android makefile:

  #. You must respect the original makefile.

  #. ``abootimg`` binary must be built only for host.

  #. Find which tag(s) you should apply to this Android module.

.. hint::
   Do not forget to test abootimg binary: read the README file.
   You need a boot image. With lunch, choose a device and generated the image.

.. admonition:: Question 1

   What are the build commands you need for your development and tests ?


4. Write an advanced Android makefile
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

In the last part, I asked you to generate manually the version header. Now, the
Android makefile must generate it by itself.

#. Remove the ``version.h`` from ``abootimg`` sources.

#. Take a look to ``LOCAL_GENERATED_SOURCES`` macro. It will be your best
   friend.

Use Gerrit pull request system to submit your patches.

.. _abootimg: https://gitorious.org/ac100/abootimg.git
.. _manifest: https://android.googlesource.com/platform/manifest/
.. _gerrit: https://android-review.cri.epita.net
.. _Understanding 64-bit Builds: https://source.android.com/setup/develop/64-bit-builds
.. _Android.mk: https://developer.android.com/ndk/guides/android_mk